1. Field of the Invention
This invention relates to hearing aids, and specifically to Behind The Ear, In The Ear, In The Canal, or Completely In The Canal hearing aids which are being shielded to be resistant to electromagnetic interference produced by cellular telephones and other devices in the 800 MHz to 100 GHz frequency range.
2. Description of Related Art
The invention consists of the following: hearing aids which can be worn behind the ear, in the ear, or in the ear canal. These devices are widely known in the hearing aid industry as follows: Behind The Ear (BTE), In The Ear or All In The Ear (ITE), In The Canal (ITC), and Completely In The Canal (CIC).
This invention intends to shield these types of hearing aids from electromagnetic interference caused by cellular telephones in the 800 MHz-100 GHz frequency range by using an electrically conductive foil to shield the circuitry components. Furthermore, an electrically conductive gasket, paint or plastic could also be used to shield the circuitry components.
Also, a filtering circuit composed of inductors and capacitors is used to shield the circuitry components wherein ferrite beads or ferrite toroids are used as the inductors.
Also, a case consisting of a faceplate and a shell, the shell being made to fit in the ear, partially in the ear canal, or completely in the ear canal, and made wholly or partially of an electrically conductive material, the outside of which consists of a material such as an acrylic that produces no adverse affects when worn in the ear by most people.
The following devices are related to, but do not comprise any part of this invention: hearing aids worn elsewhere on the body other than in or behind the ear, known as xe2x80x9cBody Aidsxe2x80x9d, aids which intentionally use an electric field antenna or a plane wave antenna, hearing aids which couple sound waves through the bones of the head, known as xe2x80x9cBone Conductionxe2x80x9d hearing aids, and also hearing aids which are built into eyeglass frames, and any devices which require surgery to install, such as Cochlear Implants.
FIG. 5 (Prior Art) Illustrates the elements which comprise a hearing aid. A Behind The Ear hearing aid is used for the illustration, but the same components are found in other hearing aids wherein the only difference could be the shape or size.
FIG. 5 (Prior Art) shows a hearing aid consists of an outer case 1, usually made of plastic such as Lucite (Poly Methyl Methacrylate), Non-Toxic Lucite, Poly Ethyl Methacrylate, Poly Vinyl Chloride, Silicone, or Polyethylene.
The case 1 houses and protects the internal circuitry components. The hearing aid has a battery door 3 which can be opened to replace the battery, an opening for a microphone 5, an opening for the speaker or receiver 6, and an opening for the volume control knob 7. The case 1 often has switches and controls, such as an optional telecoil pickup switch which couples the hearing aid electromagnetically to a telephone handset. The internal components 2 also consist of amplifiers and signal conditioning circuits as shown in the block diagram. These circuits contain non linear elements such as transistors. Some of the internal components are coupled by fine internal wires 10.
Besides all these openings as disclosed above, In The Ear, In The Canal, or Completely In The Canal hearing aids have a vent hole (not shown) to prevent the buildup of air pressure and moisture in the ear canal. This vent hole goes completely through the hearing aid. To build an effective hearing aid, one requires several openings due to current technology. Today""s hearing aid users are adversely affected by radio signals that are produced by cellular telephones and other devices in the 800 MHz to 100 GHz frequency range. These signals are often pulse modulated at rates of 200 Hz to 300 Hz. Conventional hearing aids can unintentionally act as radio receivers, with their internal wires 10 acting as unintentional antennas, and their nonlinear elements unintentionally acting as detection and demodulating circuits. This causes the hearing aid to produce annoying or intolerable sounds, such as a 200 Hz to 300 Hz hum.
Shapiro (U.S. Pat. No. 2,327,320) teaches a body-hearing aid with a shield against electromagnetic interference which undoubtedly is only effective for low frequency sources of electromagnetic interference such as motors, hair dryers, and possibly fluorescent lights. It should be noted that this shield would not be effective against the current ultra-high frequency signals being experienced by today""s hearing aid users. Ferrite beads and transistors were not available at this time and therefore, current circuitry components can not be shielded by the methods disclosed by Shapiro.
The invention consists of the following hearing aids which can be worn behind the ear, in the ear, or in the ear canal, these devices are widely known in the hearing aid industry as follows: Behind The Ear (BTE), In The Ear or All In The Ear (ITE), In The Canal (ITC), and Completely In The Canal (CIC). In this document, the phrase xe2x80x9chearing aid worn in the earxe2x80x9d refers to ITE, ITC, and CIC hearing aids.
This invention intends to shield these types of hearing aids from electromagnetic interference caused by cellular telephones in the 800 MHz-100 GHz frequency range by using an electrically conductive foil to shield the circuitry components. Furthermore, an electrically conductive gasket, paint or plastic could also be used to shield the circuitry components.
Also, a filtering circuit composed of inductors and capacitors is used to shield the circuitry components wherein ferrite beads or ferrite toroids are used as the inductors.
Also, a hearing aid worn in the ear consisting of a face plate and a shell, each made wholly or partly of a conductive material, and made in such a way that none of the conductive material comes in contact with the ear when the hearing aid is worn.